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<ul id="index">
  <li><a href="#NAME">NAME</a></li>
  <li><a href="#DESCRIPTION">DESCRIPTION</a>
    <ul>
      <li><a href="#Identities">Identities</a></li>
      <li><a href="#Gettable-Parameters">Gettable Parameters</a></li>
      <li><a href="#Settable-Context-Parameters">Settable Context Parameters</a></li>
    </ul>
  </li>
  <li><a href="#SEE-ALSO">SEE ALSO</a></li>
  <li><a href="#COPYRIGHT">COPYRIGHT</a></li>
</ul>

<h1 id="NAME">NAME</h1>

<p>EVP_MD-SHAKE, EVP_MD-KECCAK-KMAC - The SHAKE / KECCAK family EVP_MD implementations</p>

<h1 id="DESCRIPTION">DESCRIPTION</h1>

<p>Support for computing SHAKE or KECCAK-KMAC digests through the <b>EVP_MD</b> API.</p>

<p>KECCAK-KMAC is an Extendable Output Function (XOF), with a definition similar to SHAKE, used by the KMAC EVP_MAC implementation (see <a href="../man7/EVP_MAC-KMAC.html">EVP_MAC-KMAC(7)</a>).</p>

<h2 id="Identities">Identities</h2>

<p>This implementation is available in the FIPS provider as well as the default provider, and includes the following varieties:</p>

<dl>

<dt id="KECCAK-KMAC-128">KECCAK-KMAC-128</dt>
<dd>

<p>Known names are &quot;KECCAK-KMAC-128&quot; and &quot;KECCAK-KMAC128&quot;. This is used by <a href="../man7/EVP_MAC-KMAC128.html">EVP_MAC-KMAC128(7)</a>. Using the notation from NIST FIPS 202 (Section 6.2), we have <span style="white-space: nowrap;">KECCAK-KMAC-128(M, d)</span> = <span style="white-space: nowrap;">KECCAK[256](M || 00, d)</span> (see the description of KMAC128 in Appendix A of NIST SP 800-185).</p>

</dd>
<dt id="KECCAK-KMAC-256">KECCAK-KMAC-256</dt>
<dd>

<p>Known names are &quot;KECCAK-KMAC-256&quot; and &quot;KECCAK-KMAC256&quot;. This is used by <a href="../man7/EVP_MAC-KMAC256.html">EVP_MAC-KMAC256(7)</a>. Using the notation from NIST FIPS 202 (Section 6.2), we have <span style="white-space: nowrap;">KECCAK-KMAC-256(M, d)</span> = <span style="white-space: nowrap;">KECCAK[512](M || 00, d)</span> (see the description of KMAC256 in Appendix A of NIST SP 800-185).</p>

</dd>
<dt id="SHAKE-128">SHAKE-128</dt>
<dd>

<p>Known names are &quot;SHAKE-128&quot; and &quot;SHAKE128&quot;.</p>

</dd>
<dt id="SHAKE-256">SHAKE-256</dt>
<dd>

<p>Known names are &quot;SHAKE-256&quot; and &quot;SHAKE256&quot;.</p>

</dd>
</dl>

<h2 id="Gettable-Parameters">Gettable Parameters</h2>

<p>This implementation supports the common gettable parameters described in <a href="../man7/EVP_MD-common.html">EVP_MD-common(7)</a>.</p>

<h2 id="Settable-Context-Parameters">Settable Context Parameters</h2>

<p>These implementations support the following <a href="../man3/OSSL_PARAM.html">OSSL_PARAM(3)</a> entries, settable for an <b>EVP_MD_CTX</b> with <a href="../man3/EVP_MD_CTX_set_params.html">EVP_MD_CTX_set_params(3)</a>:</p>

<dl>

<dt id="xoflen-OSSL_DIGEST_PARAM_XOFLEN-unsigned-integer">&quot;xoflen&quot; (<b>OSSL_DIGEST_PARAM_XOFLEN</b>) &lt;unsigned integer&gt;</dt>
<dd>

<p>Sets the digest length for extendable output functions. The length of the &quot;xoflen&quot; parameter should not exceed that of a <b>size_t</b>.</p>

<p>For backwards compatibility reasons the default xoflen length for SHAKE-128 is 16 (bytes) which results in a security strength of only 64 bits. To ensure the maximum security strength of 128 bits, the xoflen should be set to at least 32.</p>

<p>For backwards compatibility reasons the default xoflen length for SHAKE-256 is 32 (bytes) which results in a security strength of only 128 bits. To ensure the maximum security strength of 256 bits, the xoflen should be set to at least 64.</p>

</dd>
</dl>

<h1 id="SEE-ALSO">SEE ALSO</h1>

<p><a href="../man3/EVP_MD_CTX_set_params.html">EVP_MD_CTX_set_params(3)</a>, <a href="../man7/provider-digest.html">provider-digest(7)</a>, <a href="../man7/OSSL_PROVIDER-default.html">OSSL_PROVIDER-default(7)</a></p>

<h1 id="COPYRIGHT">COPYRIGHT</h1>

<p>Copyright 2020-2023 The OpenSSL Project Authors. All Rights Reserved.</p>

<p>Licensed under the Apache License 2.0 (the &quot;License&quot;). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p>


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